Corridors of Mei-Yu-Season Rainfall over Eastern China

Abstract

Successive mesoscale convective systems may develop for several days during the mei-yu season (June–July) over eastern China. They can yield excessive rainfall in a narrow latitudinal band (called a corridor), causing severe floods. The climatology of rainfall corridors and related environmental factors are examined using 20 yr of satellite rainfall and atmospheric data. A total of 93 corridors are observed over eastern China, with maximum occurrence at 27°–31°N. They typically last 2–3 days, but some persist ≥4 days, with an extreme event lasting 11 days. These multiday convective episodes exhibit primary and secondary peaks in the morning and afternoon, respectively, with a diurnal cycle that is in contrast to other afternoon-peak rain events. On average, the corridors occur in ~23% days of the mei-yu season, but they can contribute ~51% of the total rainfall. They also vary with years and explain ~70% of the interannual variance of mei-yu-season rainfall. Composite analyses show that most corridors develop along zonally oriented quasi-stationary mei-yu fronts over central China where monsoon southwesterlies converge with northerly anomalies from the midlatitudes. The monsoon flow accelerates at ~0200 LST and forms a regional wind maximum or low-level jet over South China, which induces moisture flux convergence in morning-peak corridors. The nocturnal acceleration is less evident for afternoon-peak corridors. The mei-yu front and monsoon southwesterlies also influence the corridor’s duration, which is regulated by a dipole of geopotential anomalies, with positive in the tropics and negative in the midlatitudes. The dipole expresses a joint influence of the blocking patterns in midlatitudes and the El Niño–related anomalous high over the western Pacific Ocean, and the dipole's intensity explains well the interannual variations of the corridors.

Record‐Breaking Meiyu Rainfall Around the Yangtze River in 2020 Regulated by the Subseasonal Phase Transition of the North Atlantic Oscillation

“…However, the extremely enhanced Meiyu rainfall can induce severe flooding and cause great damage in East Asian countries. Therefore, the multiscale variability of Meiyu activity and its prediction has become one of the most important issues in these countries (Chen et al, 2017;Ding et al, 2020;Liu et al, 2020).…”

High‐resolution global climate simulations: Representation of cities

“…In June and July, the analysis region centred on Shanghai is affected by meso‐scale convective systems associated with the passage of the Meiyu front, which results in very intense localized rainfall for short durations (e.g. Guan et al ., 2020). While the climate model can resolve the Meiyu frontal system and its passage through the region (A. Volonté, pers.…”

Spatiotemporal patterns of synchronous heavy rainfall events in East Asia during the Baiu season

“…We emphasize that previous related works (e.g., Ozturk et al, 2018Ozturk et al, , 2019 have employed a different event-based similarity measure called event synchronization strength (ESS) (Quiroga et al, 2002), which is based on a similar rationale as our event coincidence rates. Recent studies have revealed that ESS can provide systematically biased estimates of the strength of event synchrony in the presence of temporally clustered events, i.e., events recorded at subsequent time steps (Hassanibesheli and Donner, 2019;Odenweller and Donner, 2020;Wolf et al, 2020). This effect needs to be corrected for either by employing a more sophisticated definition of an event or by declustering the event sequences obtained by simple thresholding prior to quantifying their mutual similarity (Boers et al, 2014a;Wolf et al, 2020).…”